Simple, fast, and simultaneous determination of orthophosphate, pyrophosphate, and tripolyphosphate by capillary electrophoresis with capacitively coupled contactless conductivity detection.

This work describes a novel analytical method using capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C4D) for simultaneous, simple, and rapid determination of three inorganic phosphates (orthophosphate, pyrophosphate, and tripolyphosphate) widely used as food additives and in pharmaceutical formulations. A background electrolyte composed of 0.5 mol L-1 acetic acid provided fast separation (around 3.0 min) and good separation efficiency and peak resolution. Linearity in the concentration range of 10-500 mg L-1 was confirmed by the coefficients of determination (R2) higher than 0.99. The limits of detection varied from 0.41 to 0.58 mg L-1. The accuracy of the proposed method was assessed by recovery tests conducted at three concentration levels in tap water samples, food, and personal hygiene products. Recovery values varying from 81% to 118% were achieved, indicating an acceptable accuracy. The proposed CE-C4D successfully determined the three inorganic phosphates in the analyzed samples.

Capillary electrophoresis with capacitively coupled contactless conductivity detection (C4 D) for rapid and simple determination of lactate in sweat.

An analytical method based on capillary electrophoresis (CE) using capacitively coupled contactless conductivity detection (C4 D) was developed and validated for fast, straightforward, and reliable determination of lactate in artificial and human sweat samples. The background electrolyte was composed of equimolar concentrations (10 mmol/L) of 2-(N-morpholino)ethanesulfonic acid and histidine, with 0.2 mmol/L of cetyltrimethylammonium bromide as electroosmotic flow inverter. The limit of detection and quantification were 3.1 and 10.3 µmol/L, respectively. Recoveries in the 97 to 118% range were obtained using sweat samples spiked with lactate at three concentration levels, indicating an acceptable accuracy. The intraday and interday precisions were 1.49 and 7.08%, respectively. The proposed CE-C4 D method can be a starting point for monitoring lactate concentrations in sweat samples for diagnostics, physiological studies, and sports performance assessment applications.

The Enantiomeric Discrimination of 5-Hexyl-2-methyl-3,4-dihydro-2H-pyrrole by Sulfobutyl ether-ß-cyclodextrin: A Case Study.

1-Pyrrolines are important intermediates of active natural products, such as the 2,5-dialkyl-1-pyrroline derivatives found in fire ant venoms. Here, 5-hexyl-2-methyl-3,4-dihydro-2H-pyrrole was synthesized by the enzymatic transamination/cyclization of 2,5-undecadione, and enantiodifferenciation was successfully achieved by capillary electrophoresis with sulfobutyl ether-ß-cyclodextrin as the chiral selector. The rationale of the enantiomeric discrimination was based on the results of a docking simulation that revealed the higher affinity of (S)-5-hexyl-2-methyl-3,4-dihydro-2H-pyrrole for the sulfobutyl ether-ß-cyclodextrin.

Instrumentation design for hydrodynamic sample injection in microchip electrophoresis: a review.

Reproducible and representative sample injection in microchip electrophoresis has been a bottleneck for quantitative analytical applications. Electrokinetic sample injection is the most used because it is easy to perform. However, this injection method is usually affected by sample composition and the bias effect. On the other hand, these drawbacks are overcome by the hydrodynamic (HD) sample injection, although this injection mode requires HD flow control. This review gives an overview of the basic principles, the instrumentation designs, and the performance of HD sample injection systems for microchip electrophoresis.

Polyester-toner electrophoresis microchips with improved analytical performance and extended lifetime.

This paper reports the fabrication of polyester-toner (PT) electrophoresis microchips with improved analytical performance and extended lifetime. This has been achieved with a better understanding about the EOF generation and the influence of some parameters including the channel dimensions (width and depth), the injection mode, and the addition of organic solvent to the running buffer. The analytical performance of the PT devices was investigated using a capacitively coupled contactless conductivity detector and inorganic cations as model analytes. The proposed devices have exhibited EOF values of (3.4 ± 0.2) × 10(-4) cm(2) V(-1) s(-1) with good stability over 25 consecutive runs. It has been found that the EOF magnitude depends on the channel dimension, i.e. the wider the channel, the higher the EOF value. The separation efficiency for inorganic cations ranged from 13 000 to 50 000 plates/m. The LOD found for K(+) , Na(+) , and Li(+) were 4.2, 7.3, and 23 µM, respectively. In addition, the same PT device has been used by three consecutive days. Lately, due to improved analytical performance, it was carried out by the first time the detection of inorganic cations in real samples such as energetic drinks and pharmaceutical formulations.